Sub DupParaTwoWay()
  Dim aRngPara As Range, aRng As Range, iEqual As Integer, iPlus As Integer, iMinus As Integer
  Set aRngPara = Selection.Paragraphs(1).Range
  iEqual = InStr(aRngPara.Text, "=")
  iPlus = InStr(aRngPara.Text, "+")
  iMinus = InStr(aRngPara.Text, "-")
  If iEqual > 0 Then
    Set aRng = ActiveDocument.Range(aRngPara.Start, aRngPara.Start + iEqual)
    If iPlus > 0 Then
      aRngPara.InsertParagraphBefore
      aRngPara.Collapse Direction:=wdCollapseStart
      aRngPara.FormattedText = aRng.FormattedText
      If Len(aRngPara.Paragraphs(1).Range.Text) = 1 Then aRngPara.Paragraphs(1).Range.Delete
      aRngPara.Characters(iPlus).Text = "-"
    ElseIf iMinus > 0 Then
      aRngPara.InsertParagraphAfter
      aRngPara.Collapse Direction:=wdCollapseEnd
      aRngPara.MoveEnd Unit:=wdCharacter, Count:=-1
      aRngPara.FormattedText = aRng.FormattedText
      aRngPara.Characters(iMinus).Text = "+"
    End If
    aRngPara.Select
  End If
End Sub